Choice between reliable and unreliable outcomes: mixed percentage-reinforcement in concurrent chains.

Pigeons' choices between alternatives that provided different percentages of reinforcement in mixed schedules were studied using the concurrent-chains procedure. In Experiment 1, the alternatives were terminal-link schedules that were equal in delay and magnitude of reinforcement, but that provided different percentages of reinforcement, with one schedule providing, reinforcement twice as reliably as the other. All pigeons preferred the more reliable schedule, and their level of preference was not systematically affected by variation in the absolute percentage values, or in the magnitude of reinforcement. In Experiment 2, preference for a schedule providing 100% reinforcement over one providing 33% reinforcement increased systematically with increases in the duration of the terminal links. In contrast, preference decreased systematically with increases in the duration of the initial links. Experiment 3 examined choice with equal percentages of reinforcement but unequal delays to reinforcement. Preference for the shorter delay to reinforcement was not systematically affected by variation in the absolute percentage of reinforcement. The overall pattern of results supported predictions based on an extension of the delay-reduction hypothesis to choice procedures involving mixed schedules of percentage reinforcement.     

Delay reduction: current status.

Delay-reduction theory states that the effectiveness of a stimulus as a conditioned reinforcer may be predicted most accurately by the reduction in time to primary reinforcement correlated with its onset. We review support for the theory and then discuss two new types of experiments that assess it. One compares models of choice in situations wherein the less preferred outcome is made more accessible; the other investigates whether frequency of conditioned reinforcement affects choice beyond the effect exerted by frequency of primary reinforcement.     

Response-independent Events In The Behavior Stream

The metaphor of the behavior stream provides a framework for studying the effects of response-independent food presentations intruded into an environment in which operant responding of pigeons was maintained by variable-interval schedules. In the first two experiments, response rates were reduced when response-independent food was intruded during the variable-interval schedule according to a concomitantly present fixed-time schedule. These reductions were not always an orderly function of the percentage of response-dependent food. Negatively accelerated patterns of key pecking across the fixed-time period occurred in Experiment 1 under the concomitant fixed-time variable-interval schedules. In Experiment 2, positively and negatively accelerated and linear response patterns occurred even though the schedules were similar to those used in Experiment 1. The variable findings in the first two experiments led to three subsequent experiments that were designed to further illuminate the controlling variables of the effects of intruded response-independent events. When the fixed and variable schedules were correlated with distinct operanda by employing a concurrent fixed-interval variable-interval schedule (Experiment 3) or with distinct discriminative stimuli (Experiments 4 and 5), negatively accelerated response patterns were obtained. Even in these latter cases, however, the response patterns were a joint function of the physical separation of the two schedules and the ratio of fixed-time or fixed-interval to variable-interval schedule food presentations. The results of the five experiments are discussed in terms of the contributions of both reinforcement variables and discriminative stimuli in determining the effects of intruding response-independent food into a stream of operant behavior.     

EMPLOYING TASK ARRANGEMENTS AND VERBAL CONTINGENCIES TO PROMOTE VERBALIZATIONS BETWEEN RETARDED CHILDREN1

This study investigated the effects of arranging task events for interdependence, to increase the probability of social responding. During task interdependence, the subjects, participating in dyads and a four-person group, obtained task materials (a puzzle piece) from their partner before completing their task (appropriately placing the puzzle piece). The verbal contingency required a verbal request to precede a subject's receiving a task material from his partner. The verbal contingency yoked with task interdependence made task completion contingent on the appropriate verbalization. The findings from two experiments suggested that task interdependence was sufficient to increase partner-directed verbalizations for three of the four subjects. When the verbal contingency was added, all subjects increased their requests and other verbalizations to partner. Applied to a four-person group, the verbal contingency yoked with varying levels of task interdependence correspondingly affected the pattern and level of group communications. The greater the task interdependence, i.e., the more members each subject depended on to complete his task, the more complex the social network of verbal contacts, and the higher the level of both requests and other verbalizations for the group.     

One Roof,Three Generations: Grandparental Co-residence and Child Outcomes in China

This study examined the association between grandparental co-residence and child academic and behavioral outcomes using a sample from Shanghai, China (n = 1,763), and was built on two theoretical perspectives: intergenerational solidarity theory and the contextual model of family stress. These models integrate the impact of residential and relational proximity to grandparents on child well-being and underscore the importance of family context. This study also explored the moderating effects of family resources using proxies that prior theoretical and empirical studies have found to be important to such associations: family income, parental education, hukou status, and subjective social status. Results indicated that among families without co-residing grandparents, rural and low-income parents reported their children to have more externalizing behavioral issues than their respective urban and non-low-income counterparts. In addition, children who resided in poorly resourced families (i.e., low family income, low parental education, low subjective social status, or rural hukou status) tended to benefit from living with grandparents compared to their well-resourced counterparts in terms of lower externalizing and internalizing behaviors reported by teachers. These results do not negate the potential beneficial effects of living with grandparents for children in well-resourced environments. Implications for practice and policy, as well as future research directions, are discussed.     

Residence arrangements and well-being: a study of Norwegian adolescents

The purpose of this study was to assess any differences in psychosocial problems among adolescents living with both parents, or with their mother or their father. Any benefits of living with a same-sex parent compared to a parent of the opposite sex, was also analysed. A total of 1,686 adolescents aged 14-15 years participated from 29 schools in Hordaland county, including schools in downtown Bergen and more rural areas. The findings revealed significantly more psychosocial problems among the adolescents living with one parent compared to both parents. Significant differences were also observed between adolescents living in mother custody compared to father custody, indicating more problems among the latter group. Furthermore, girls living with their father had significantly higher levels of psychological symptoms, compared to boys in father custody. Similarly, boys living with their father were involved in more stealing behavior than girls in father custody. However, residence arrangement accounted for only a limited proportion of the variance in the adolescents' psychosocial problems, indicating large within-group variance and overlap between the different custody groups.     

今本《周易》卦序排列数学规律新探

今本《周易》六十四卦卦序是依据什么道理排列出来的,迄今仍然没有一个完美的解答。本文尝试把卦序问题作为一个数学问题去考虑,探讨卦序的制作者所依据的数学思想与技巧。《六十四卦错综图》是我们研究序卦最重要的参考图,并指出十对三明三阳卦在序卦排列中起着骨架作用．无论是十对三明三阳卦,还是围绕这十对卦左右的其它卦,其排列在序数配置、卦区划分和爻画布排等诸多方面都蕴含着丰富的数学内容,充分反映了序卦的制作者运用数学技巧的娴熟技艺和精妙构想。     

Stimulus Equivalence: Effects Of A Default-response Option On Emergence Of Untrained Stimulus Relations

Human subjects were exposed to a concurrent-chains schedule in which reinforcer amounts, delays, or both were varied in the terminal links, and consummatory responses were required to receive points that were later exchangeable for money. Two independent variable-interval 30-s schedules were in effect during the initial links, and delay periods were defined by fixed-time schedules. In Experiment 1, subjects were exposed to three different pairs of reinforcer amounts and delays, and sensitivity to reinforcer amount and delay was determined based on the generalized matching law. The relative responding (choice) of most subjects was more sensitive to reinforcer amount than to reinforcer delay. In Experiment 2, subjects chose between immediate smaller reinforcers and delayed larger reinforcers in five conditions with and without timeout periods that followed a shorter delay, in which reinforcer amounts and delays were combined to make different predictions based on local reinforcement density (i.e., points per delay) or overall reinforcement density (i.e., points per total time). In most conditions, subjects' choices were qualitatively in accord with the predictions from the overall reinforcement density calculated by the ratio of reinforcer amount and total time. Therefore, the overall reinforcement density appears to influence the preference of humans in the present self-control choice situation.     

Profiles of commitment in standard and fixed-term employment arrangements: Implications for work outcomes

This paper develops and tests a framework for understanding the relative importance and predictive efficacy of commitment to one’s profession, organization, supervisor and job in both standard and fixed-term employment arrangements. Drawing from the commitment and employment arrangement literatures, we test a set of hypotheses identifying distinct patterns of commitments (i.e., commitment profiles) to these four targets that should yield desired work-related outcomes in standard and fixed-term employment arrangements. We test our hypotheses using latent profile analysis on data collected from two Finnish universities (N1 = 235, N2 = 233). A high macro profile, characterized by high commitment to profession, organization and job, and moderate commitment to supervisor, emerged for employees in standard employment relationships, and this profile was associated with significantly higher positive work behaviours and work effort and lower turnover intentions than the other profiles. For employees with fixed-term employment contracts, a high cosmopolitan profile emerged, characterized by high commitment to the profession and job and low commitment to the organization and supervisor. For these employees, this profile was associated with positive work behaviours and work effort comparable to the high macro profile. Implications for theory, research and practice are discussed.